KR101603213B1 - Method for correcting handshaking and digital photographing apparatus adopting the method - Google Patents

Abstract

The camera shake correction method of the digital photographing apparatus according to the present invention includes steps (a) and (b). In step (a), when the exposure time to be applied for photographing is shorter than the reference time, the camera shake correction is performed by the optical image stabilization (OIS) technique. In step (b), if the exposure time to be applied for photographing is longer than the reference time, the camera shake correction is performed by the optical image stabilization (OIS) technique and the digital image stabilization (DIS) technique.

Description

TECHNICAL FIELD [0001] The present invention relates to a camera shake correcting method and a digital photographing apparatus employing the method,

The present invention relates to a camera shake correction method of a digital photographing apparatus and a digital photographing apparatus employing the method.

A typical digital photographing device, for example, a digital camera has an image shake correction function.

Such an image stabilization function is achieved by adopting any one of the two techniques in the digital photographing apparatus.

One such technique is Optical Image Stabilization (OIS). This technique is a hardware technique that extracts a camera shake vector using a gyro sensor and moves the optical system etc. in advance in accordance with the extracted camera shake vector. The camera shake correction performance is excellent.

However, since a very fast and precise signal processing element and a driving element are required, there is a problem that the manufacturing cost for the image stabilization function is very high.

Another technique is the Digital Image Stabilization (DIS) technique. This technique is a software technique in which a main controller in a digital photographing apparatus analyzes and corrects an input image signal. Therefore, the digital image stabilization (DIS) technique has a problem in that the image stabilization performance is lower than that of the optical image stabilization (OIS) technique although the manufacturing cost is low for the image stabilization function.

An object of the present invention is to provide a camera shake correcting method and a digital photographing apparatus employing the method, which can efficiently improve the performance while lowering the manufacturing cost for the camera shake correction function of the digital photographing apparatus.

In order to achieve the above object, an image shake correction method of a digital photographing apparatus of the present invention includes steps (a) and (b).

In step (a), when the exposure time to be applied for photographing is shorter than the reference time, the camera shake correction is performed by an optical image stabilization (OIS) technique.

In step (b), if the exposure time to be applied for photographing is longer than the reference time, the camera shake correction is performed by the optical image stabilization (OIS) technique and the digital image stabilization (DIS) technique.

The digital photographing apparatus employing the camera shake correction method includes an optical system, a photoelectric conversion unit, an analog-digital conversion unit, an optical image stabilization (OIS) unit, and a main control unit.

The photoelectric conversion unit converts light from the optical system into an electrical analog signal.

The analog-to-digital converter converts an analog signal from the photoelectric conversion unit into digital image data.

Wherein the main control unit enables the operation of the optical image stabilization (OIS) unit if the exposure time to be applied for photographing is shorter than the reference time, and if the exposure time to be applied for photographing is longer than the reference time, OIS) unit and performs digital image stabilization (DIS) at the same time.

According to the camera shake correcting method and the digital photographing apparatus employing this method of the present invention, it is possible to efficiently improve the performance while lowering the manufacturing cost for the camera shake correction function of the digital photographing apparatus. The reason for this is as follows.

As is well known, in the still image shooting operation or the moving image shooting operation of the digital photographing apparatus, the exposure time to be applied is automatically calculated by the shutter speed or the like. Here, the degree of camera shake is proportional to the exposure time to be applied for still image or movie shooting.

Therefore, when the exposure time to be applied for photographing is shorter than the reference time, the degree of camera shake is relatively weak. Therefore, even if the performance of the optical image stabilization (OIS) unit of the present invention is relatively low, the camera shake correction can be performed well . Here, since the main control unit of the digital photographing apparatus of the present invention does not perform digital image stabilization (DIS) at the same time, the operation load of the main control unit is reduced and the operation speed of the main control unit can be improved.

When the exposure time to be applied for photographing is longer than the reference time, the degree of camera shake is relatively strong. Therefore, if the performance of the optical image stabilization (OIS) unit is relatively low and the performance of the optical image stabilization unit is relatively low, the camera shake correction may be insufficient. However, since the main control unit of the digital photographing apparatus of the present invention performs digital image stabilization (DIS) at the same time, even if the performance of the optical image stabilization (OIS) unit of the present invention is relatively inexpensive and low, It can be good.

1 is a diagram showing the overall configuration of a digital photographing apparatus employing a camera shake correction method according to the present invention.
2 is a view showing an incidence side structure of the digital photographing apparatus of FIG.
3 is a block diagram showing the internal configuration of the optical image stabilization (OIS) driver of FIG.
4 is a flowchart showing a camera shake correction method of the digital camera processor as the main control unit of FIG.
5 is a graph showing the shaking motion correction method of FIG.
FIG. 6 is a diagram for explaining a digital image stabilization (DIS) method at the time of capturing a still image in step S45 of FIG.
7 is a flowchart showing a digital image stabilization (DIS) method at the time of capturing a still image in step S45 of FIG.
FIG. 8 is a diagram for explaining a digital image stabilization (DIS) method at the time of capturing moving images in step S45 of FIG.
FIG. 9 is a flowchart showing a digital image stabilization (DIS) method at the time of shooting a moving picture in step S45 of FIG.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

1 shows the overall configuration of a digital photographing apparatus 1 employing a camera shake correction method according to the present invention. Fig. 2 shows the incidence side structure of the digital photographing apparatus 1 of Fig. The overall configuration and operation of the digital photographing apparatus 1 of FIG. 1 will be described with reference to FIGS. 1 and 2. FIG.

An optical system (OPS) including the lens unit 20 and the filter unit 41 optically processes light from a subject. The lens unit of the optical system OPS includes a zoom lens ZL, a focus lens FL, and a correction lens CL. When a user presses a zoom button included in the user input unit INP in a live-view mode or a moving picture photographing mode, a corresponding signal is input to the micro controller 512. [ Accordingly, as the microcontroller 512 controls the driving unit 510, the zoom motor Mz is driven to move the zoom lens ZL.

For example, when a wide angle-zoom signal is generated, the focal length of the zoom lens ZL is shortened to increase the angle of view, and when a telephoto-zoom signal is generated, So that the angle of view is narrowed. Here, since the position of the focus lens FL is adjusted in a state where the zoom lens ZL is set, the view angle is hardly affected by the position of the focus lens FL.

Meanwhile, in the automatic focusing mode, the core processor incorporated in the digital camera processor 507 as the main controller controls the driving unit 510 through the micro controller 512 to drive the focus motor Mf. Thus, the focus lens FL is moved. In this process, the position of the focus lens, in which the luminance differences between adjacent pixels are the largest on average, is set as the number of drive steps of the focus motor Mf. That is, the position of the focus lens in which the focus value, which is the frame contrast, is the largest is set as the drive step number of the focus motor Mf.

The correction lens CL of the lens unit 20 of the optical system OPS adjusts the refractive index of the incident light while being driven by the correction motors 593 and Mc for optical image stabilization (OIS).

Reference symbol Ma denotes a motor for driving an aperture (not shown).

In the filter section 41 of the optical system OPS, an optical low pass filter (OLPF) removes optical noise of a high frequency content. Infra-red cut filter (IRF) blocks incoming infrared light.

A photoelectric conversion unit OEC of a CCD (Charge Coupled Device) or a CMOS (Complementary Metal-Oxide-Semiconductor) converts light from the optical system OPS into an electrical analog signal. Here, the digital camera processor 507 controls the timing circuit 502 to control the operations of the photoelectric conversion unit (OEC) and the analog-digital conversion unit 501. A CDS-ADC (Correlation Double Sampler and Analog-to-Digital Converter) 501 as an analog-to-digital conversion section processes an analog signal from the photoelectric conversion section OEC, removes the high- , And generates digital image data.

The real-time clock 503 provides time information to the digital camera processor 507. The digital camera processor 507 processes the digital image data from the CDS-ADC 501 to generate digital image data classified into luminance and chroma signals.

The light emitting unit (LAMP) driven by the microcontroller 512 according to the control signals from the digital camera processor 507 includes a self-timer lamp and a photographing apparatus-state lamp.

In the DRAM (Dynamic Random Access Memory) 504, digital image data from the digital camera processor 507 is temporarily stored. An algorithm necessary for the operation of the digital camera processor 507 is stored in an EEPROM (Electrically Erasable and Programmable Read Only Memory) 505. In the memory card interface (MCI) 506, the user's memory card is detached. In the flash memory (FM), setting data necessary for the operation of the digital camera processor 507 is stored. In the memory card interface 506, the memory card is detached and removed as user's recording media.

The digital image data from the digital camera processor 507 as the main control unit is input to the LCD driver 514, thereby displaying an image on the display panel 35. [

The digital image data from the digital camera processor 507 is transmitted through the USB (Universal Serial Bus) connection unit 21a or the RS232C interface 508 and the connection unit 21b through the serial communication in the interface unit 21 And can be transmitted as a video signal through the video filter 509 and the video output unit 21c.

The audio processor 513 outputs the audio signal from the microphone MIC to the digital camera processor 507 or the speaker SP and outputs the audio signal from the digital camera processor 507 to the speaker SP.

On the other hand, the micro controller 512 controls the operation of the flash controller 511 in accordance with the signal from the flash-light amount sensor 19 to drive the flash 12. [

As described above, the correction lens CL of the lens unit 20 of the optical system OPS adjusts the refractive index of the incident light while being driven by the correction motors 593 and Mc for optical image stabilization (OIS).

Here, the optical image stabilization (OIS) section includes a gyro sensor 591, GS, an optical image stabilization (OIS) driver 592, and correction motors 593, Mc.

The gyro sensors 591 and GS generate the angular speed signal Sav corresponding to the shaking of the digital photographing apparatus 1. [

The digital camera processor 507 (DCP) as the main control unit generates the enable signal Sen for controlling the operation of the optical image stabilization (OIS) driver 592.

When an enable command is generated from the digital camera processor 507 (DCP), the optical image stabilization (OIS) driver 592 extracts the camera shake vector according to the angular velocity signal from the gyro sensors 591 and GS, The correction motors 593 and Mc are driven in correspondence with the camera shake expected vector.

The correction motors 593 and Mc which may be replaced by actuators operate in accordance with the drive signal Smt from the optical image stabilization (OIS) driver 592 and are supplied to the lens unit 20 of the optical system OPS, And adjusts the direction of the correction lens CL of FIG.

Here, the digital camera processor 507 (DCP) as the main control unit enables the operation of the optical image stabilization (OIS) units 591 to 593 if the exposure time to be applied for photographing is shorter than the reference time, When the exposure time to be applied for photographing is longer than the reference time, the operation of the optical image stabilization (OIS) units 591 to 593 is enabled and the digital image stabilization (DIS) is performed.

FIG. 3 shows the internal configuration of the optical image stabilization (OIS) driver 592 of FIG.

1 and 3, the optical image stabilization (OIS) driver 592 includes an integrating unit 31, a digital filter 32, a driving circuit 34, and a control unit 33.

The integrator 31 integrates the angular speed signal Sav from the gyro sensors 591 and GS to generate the angle signal Sa1.

The digital filter 32 removes the noise included in the angle signal Sa1 from the integrator 31. [

The driving circuit 34 drives the correction motors 593, Mc.

The control unit 33 extracts the camera shake prediction vector in accordance with the angle signal Sa2 from the digital filter 32 and controls the driving circuit 34 in accordance with the extracted camera shake vector.

FIG. 4 is a flowchart showing a camera shake correction method of the digital camera processor 507 (DCP) as the main control unit in FIG. 5 is a graph showing the shaking motion correction method of FIG. 5, reference character Tlim denotes an upper limit value of the exposure time.

Referring to FIGS. 4 and 5, a camera shake correction method of the digital camera processor 507 (DCP) as the main control unit of FIG. 1 will be described as follows.

In the case of the still image or moving image photographing mode (step S41), the digital camera processor 507 (DCP) judges whether the exposure time to be applied is shorter than 1/30 second as the threshold time (step S42).

Here, the above critical time is an estimated time at which the shaking motion can not be generated, and is set by the following equation (1).

In Equation (1), the converted focal length for the 35 mm film is set by the following equation (2).

In the above equation (2), Daf denotes the focal length of the actual focus lens (FL in FIG. 2), L35 denotes the diagonal length of the 35 mm film, and Lac denotes the diagonal length of the actual photoelectric conversion portion (OEC in FIG. 2).

For reference, the diagonal length (L35) of the 35 mm film is 43.3 mm because the horizontal length of the 35 mm film is 36 mm and the vertical length is 24 mm. 2), the focal distance Daf of the actual focus lens (FL in Fig. 2) is 4.509 mm and the diagonal length Lac of the photoelectric conversion portion (OEC in Fig. 2) Is 5.78488 mm.

Therefore, in the case of this embodiment, the threshold time is set to 1/30 second.

Therefore, when the exposure time to be applied for photographing is shorter than 1/30 second, which is the critical time, the efficiency can be achieved by not performing the camera shake correction (step S42).

If the exposure time to be applied for photographing is longer than the critical time of 1/30 second, the digital camera processor 507 (DCP) determines whether the exposure time to be applied is shorter than 1/8 second, which is the reference time (step S43).

Next, when the exposure time to be applied for photographing is longer than 1/30 second, which is the critical time, and shorter than 1/8 second, which is the reference time, the digital camera processor 507 (DCP) drives the optical image stabilization (OIS) (Step S44). Accordingly, the camera shake correction is performed by an optical image stabilization (OIS) technique.

Accordingly, when the exposure time to be applied for photographing is longer than 1/30 second, which is the critical time, and shorter than 1/8 second, which is the reference time, the degree of camera shake is relatively weak, so that the performance of the optical image stabilization (OIS) units 591 to 593 It is possible to correct the shaking motion even if it is relatively inexpensive. In this case, since the digital camera processor 507 (DCP) as the main control unit does not simultaneously perform the digital image stabilization (DIS), the operation load of the digital camera processor 507 (DCP) is reduced and the digital camera processor 507 Can also be improved.

The digital camera processor 507 (DCP) may enable the optical image stabilization (OIS) driver 592 if the exposure time to be applied for photographing is equal to or longer than the reference time of 1/8 second and the upper limit time (Tlim) , And camera shake correction is performed in a double manner by the digital image stabilization (DIS) technique (step S45).

When the exposure time to be applied for photographing is equal to or longer than 1/8 sec, which is the reference time, and is less than the upper limit time (Tlim), the degree of camera shake is relatively strong, so that the performance of the optical image stabilization (OIS) units 591 to 593 is relatively low If it is inexpensive, the camera shake correction may be insufficient. However, since the digital camera processor 507 (DCP) as the main control unit simultaneously performs the digital image stabilization (DIS), even if the performance of the optical image stabilization (OIS) units 591 to 593 is relatively low, .

FIG. 6 is a diagram for explaining a digital image stabilization (DIS) method at the time of capturing a still image in step S45 of FIG. 6, reference numeral 61 denotes a movement curve of an actual feature point. 7 is a flowchart showing a digital image stabilization (DIS) method at the time of capturing a still image in step S45 of FIG.

A method of stabilizing a digital image (DIS) at the time of still image shooting will be described with reference to FIGS. 1, 6 and 7.

When the image capturing signal is input by the user's shutter pressing (step S71), the digital camera processor 507 (DCP) as the main control unit captures the first image F1 at the applicable exposure time (step S72).

Next, the digital camera processor 507 (DCP) captures a plurality of second images F2a to F2e at different exposure times (step S73).

Next, the digital camera processor 507 (DCP) obtains a motion vector between the plurality of captured second images F2a to F2e (step S74).

Next, the digital camera processor 507 (DCP) obtains a representative second image whose motion has been corrected according to the obtained motion vector (step S75).

Next, the digital camera processor 507 (DCP) synthesizes the first image F1 and the representative second image to obtain a third image (step S76).

Then, the digital camera processor 507 (DCP) outputs the obtained third image as a camera-shake corrected image (step S77).

FIG. 8 is a diagram for explaining a digital image stabilization (DIS) method at the time of capturing moving images in step S45 of FIG. In FIG. 8, reference numeral 81 denotes a movement curve of actual feature points, F1 to F6 denote a series of input frame images, and SR1 to SR6 denote reduced images of respective frames, respectively.

FIG. 9 shows a digital image stabilization (DIS) method at the time of capturing moving images in step S45 of FIG.

1, 8, and 9, a digital image stabilization (DIS) method at the time of capturing moving images will be described as follows.

When the photographing start signal is inputted by the user's shutter pressing (step S91), the digital camera processor 507 (DCP) as the main control unit judges whether the frame image F2 is inputted (step S92).

Next, when the frame image F1 is input, the average gradation and the reduced image SR2 of the input frame image F2 are obtained (steps S93 and S94).

Next, the digital camera processor 507 (DCP) determines whether the difference between the average gradation of the previous frame F1 and the average gradation of the current frame F2 is smaller than the threshold value (step S95).

Here, when the difference between the average gradation of the previous frame F1 and the average gradation of the current frame F2 is equal to or larger than the threshold value, the digital camera processor 507 (DCP) judges that a large change of the input image has occurred, Calibration is not performed.

Next, when the difference between the average gradation of the previous frame F1 and the average gradation of the current frame F2 is less than the threshold value, the digital camera processor 507, DCP calculates the center of the reduced image of the current frame F2 The image of the current frame F2 is moved so as to coincide with the center of the reduced image of the previous frame F1 (step S96).

Then, the digital camera processor 507 (DCP) repeats the above steps S92 to S96 until the photographing end signal is inputted by the user pressing the shutter (step S97).

INDUSTRIAL APPLICABILITY As described above, according to the camera shake correcting method and the digital photographing apparatus employing the camera shake correction method according to the present invention, it is possible to efficiently improve the performance while lowering the manufacturing cost for the camera shake correction function of the digital photographing apparatus. The reason for this is as follows.

As is well known, in the still image shooting operation or the moving image shooting operation of the digital photographing apparatus, the exposure time to be applied is automatically calculated by the shutter speed or the like. Here, the degree of camera shake is proportional to the exposure time to be applied for still image or movie shooting.

Therefore, when the exposure time to be applied for photographing is shorter than the reference time, the degree of camera shake is relatively weak, so that even if the performance of the optical image stabilization (OIS) unit according to the present invention is relatively low, . Here, since the main control unit of the digital photographing apparatus according to the present invention does not perform digital image stabilization (DIS) at the same time, the operation load of the main control unit is reduced and the operation speed of the main control unit can be improved.

When the exposure time to be applied for photographing is longer than the reference time, the degree of camera shake is relatively strong. Therefore, if the performance of the optical image stabilization (OIS) unit is relatively low and the performance of the optical image stabilization unit is relatively low, the camera shake correction may be insufficient. However, since the main control unit of the digital photographing apparatus according to the present invention simultaneously performs digital image stabilization (DIS), even if the performance of the optical image stabilization (OIS) unit according to the present invention is relatively low, It can be good.

The present invention is not limited to the above-described embodiments, but can be modified and improved by those skilled in the art within the spirit and scope of the invention defined in the claims.

It can be used for shake correction in precision measuring instruments.

1 ... Digital photographing device, 12 ... Flash,
19 ... flash-light amount sensor, 20 ... lens part,
MIC ... Microphone, SP ... Speaker,
31 ... integral part, 32 ... digital filter,
33 ... control unit, 34 ... drive circuit,
35 ... display panel, OPS ... optical system,
OEC ... Photoelectric converter, M _Z ... Zoom motor,
Mf ... Focus motor, Ma ... Aperture motor,
501 ... analog-digital conversion section, 502 ... timing circuit,
503 ... real time clock, 504 ... DRAM,
505 ... EEPROM, 506 ... memory card interface,
507 ... digital camera processor, 508 ... RS232C interface,
509 ... video filter, 21a ... USB connection,
21b ... RS232C connection section, 21c ... a video output section,
510 ... driving unit, 511 ... flash controller,
512 ... microcontroller, INP ... user input,
LAMP ... emitting portion, 513 ... audio processor,
514 ... LCD driver, 592 ... optical image stabilization (OIS) driver,
591 ... gyro sensor, 593 ... correction motor,
62 ... flash memory.

Claims (9)

delete delete delete delete delete Optical system,
A photoelectric conversion unit for converting light from the optical system into an electrical analog signal,
An analog-to-digital converter for converting an analog signal from the photoelectric converter into digital image data,
Optical Image Stabilization (OIS), and
The operation of the optical image stabilization (OIS) unit is enabled if the exposure time to be applied for photographing is shorter than the reference time, and the operation of the optical image stabilization (OIS) unit is performed when the exposure time to be applied for photographing is longer than the reference time And a main control unit for performing digital image stabilization (DIS) at the same time. delete The method according to claim 6,
Wherein the optical system includes a lens portion and a filter portion,
Wherein the lens unit of the optical system includes a zoom lens, a focus lens, and a correction lens. 9. The apparatus of claim 8, wherein the optical image stabilization (OIS)
A gyro sensor for generating an angular velocity signal according to shaking,
An integrator for integrating an angular velocity signal from the gyro sensor to generate an angular signal,
A digital filter for removing noise included in the angle signal from the integrator,
A correction motor for driving the correction lens of the lens unit,
A drive circuit for driving the correction motor, and
And a controller for extracting a camera shake vector according to the angle signal from the digital filter and controlling the driving circuit in accordance with the extracted camera shake vector.

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